Drawing instrument



T N E M U R T s N I G N I W A R D Original Filed Jan. 31, 1935 Aug. 23,1938.

Reissued Aug. 23, 1938 UNITED STATES PATENT OFFICE DRAWING INSTRUMENTKarl Rabe, Stuttgart, Germany, assig'nor to Adolf Rosenberger, Paris,France 12 Claims.

It has hitherto been necessary when measuring areas, such as arenecessary, for example, for calculating the Weight of constructional andmachine parts, to remove the drawing, to place it on a 5 horizontalsupport and, finally, to carry out the measurement of the area by meansof a special measuring device. This procedure has been found verycomplicated and time consuming because such measurements of area arenecessary while the constructional parts are being developed and,therefore, repeated fixing on and removing of the drawing and repeatedapplication of the measuring device could not be avoided. Thearrangement, according to the invention, will make it possible to carryout such measurements of area. on any drawing-board, that is also onvertical or inclined drawing-boards by means of the drawing device. Forthis purpose the measuring device of a polarplanimeter is rotatablymounted on the guiding arms connected with the drawing head of thedrawing instrument, so as to be brought into the operative position bymeans of a simple handle. Since the drawing head is guided exactlyparallel, any desired point thereof, or of the setsquare connectedtherewith, can be chosen as the starting point for traveling round theboundary of the area. This has the advantage that all surfaces, even thelargest which have to be measured, can be dealt with in one operationwithout removing the drawing or interrupting the drawing operation. Theplanimeter constant can be freely chosen by changing the location of thetracing point to appropriate positions upon one of the guiding links 2,2', or upon some member carried thereby. In order to assure that therunning wheel of the planimeter will not pass oil the drawing surfacethe planimeter head may be mounted adjustably with respect to theguiding links 2, 2.

A constructional example of the arrangement is illustrated in detail inthe accompanying drawing, in which:

Figure 1 is an elevation of the parallelogram drawing instrument;

Figure 2 is an elevation of the measuring device seen in the directionR; and

Figure 3 is a section through the measuring device on the line IIIIII ofFigure 2.

The parallelogram drawing device illustrated consists of two parallelguiding links or arms I, I' and 2, 2 arranged in series. The rotatinglinks I, I are each connected at one end to the supporting block 3 andat the other end with an intermediate link such as the guiding ring 4 bymeans of suitable pivot means. Thus, the intermediate link or member Iwill in all positions of its pivoted supporting means remain parallel toits original position. Arm means such as the thrust arms 2, 2 are eachhinged at one end to the intermediate member 4 and at the other end to aconnecting link member such as the drawing head 5 so that the connectingmember or drawing head 5 will always remain parallel to its originalposition. The drawing head 5 carries a drawing instrument such as thesetsquare 6 which is graduated and can preferably be adjusted about themiddle point M of the drawing head 5. The measuring device of apolarplanimeter may be suitably mounted on the arm 2 by means of asleeve I. The sleeve I carries, by means of short arms 8, the bearingeyes- 9-, Ill for the measuring shaft I I. The running wheel I2 isconnected with the measuring shaft II in a known manner and the countingdisc I4 is connected through an angle drive I3. On the bearing IIJ thereis connected the Vernier disc I5, the graduations of which are adjacentto those of the running wheel I2. The sleeve 1 is rotatably andlongitudinally displaceable on the arm 2 and can be fixed by means of acatch. The latter may consist of a conical pin I6 which is forced intothe borings I8 of the arm 2 under the action of a previously tensionedspring II. The pin I6 can be lifted against the spring pressure by meansof a knob I9. In the operating position the wheel I2 rolls and slides onthe drawing surface 20. The borings I8 are distributed at definitedistances on the arm 2.

For carrying out the measurement for example, the zero point of thegraduations of one arm 6 of the setsquare is set to the starting pointof the outline K of the area and is caused to travel round the outlinein any direction. The hand rests lightly on the drawing head in order tocause the wheel I2 to move. The result is read off in a known mannerfrom the counting disc I4 and the divisions of the wheel I2. The area ofthe surface is obtained from the difference between the values read offbefore and after traveling round the curve K and after multiplying itwith the constant. When the measurement is ended the pin I6 is liftedfrom the catch by means of the knob I9 and the measuring device isturned upwards through an angle of a, so as to be put out of operationin order not to interfere with' further work on the drawing. If desired,the measuring device may be moved along the arm 2 towards the ring 4 andbrought into the operative position at this point. Care must of coursebe taken that the wheel I2 always runs onthe drawing surface 20. Thesetsquare 6 is preferably made of transparent material in order to makeit possible to travel round the outline K of the area in eitherdirection.

In Fig. l the first graduation on the horizontal scale of the drawinghead or setsquare is shown as used for the tracing point for measuringareas but since the head 5 and any member attached to it moves parallelto its original position, it is obvious that any point on head 5 or anypoint on any member attached to head 5 may be taken as the tracingpoint.

The invention is not restricted to this constructional example. Themeasuring device may be connected with both parts 2, 2' by means of acoupling rod which, of course, would have to be pivoted in such a manneras not to interfere with the parallel guiding. The measuring device canbe resiliently arranged on the arm 2 in order to keep the pressure ofthe wheel l2 on the drawing surface 20 as nearly as posssible constantand in this way save the whee1l2. Instead of the catch illustrated, anyother may be used. Other constructions of the measuring device or of thedrawing instrument also fall Within the scope of the invention in so faras these parts can be combined in a similar manner with useful results.

What I claim is:

1. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, a pair of parallel arms ofequal length each pivotally attached at one end to said support and atthe other end to said intermediate member, a link connecting member, apair of parallel links of equal length each pivotally attached at oneend to said intermediate member, said link connecting member includingtracing means adapted to be guided around the periphery of an area to bemeasured, and a planimeter running wheel supported by one of said linksin position to operate upon said surface.

2. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, a pair of arms each pivotallyattached at one end to said support and at the other end to saidintermediate member, a link connecting member, a pair of links eachpivotally attached at one end to said intermediate member and at theother end to said link connecting member, and a planimeter running wheelsupported by one of said links in position to operate upon said surface,the means for supporting said planimeter running Wheel upon one of saidlinks comprising a frame formed with bearings for said wheel and withmeans for attaching said frame to the supporting link at differentdistances from the intermediate member.

3. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, a pair of arms each pivotallyattached at one end to said support and at the other end to saidintermediate member, a connecting member, a pair of links each pivotallyattached at one end to said intermediate member and at the other end tosaid connecting member, said link connecting member including tracingmeans adapted to be guided around the periphery of an area to bemeasured, and a planimeter running wheel supported by one of said linksin position to operate upon said surface.

4. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, a pair of arms each pivotallyattached at one end to said support and at the other end to saidintermediate member, a connecting member, a pair of links each pivotallyattached at one end to said intermediate member and at the other end tosaid connecting member, and a planimeter running wheel supported by oneof said links in position to operate upon said surface, the means forsupporting said planimeter running wheel upon one of said linkscomprising a frame formed with bearings for said wheel and with meansfor pivotally attaching said frame to the supporting link so that therunning wheel may be moved away from said surface when not in use.

5. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, a pair of arms each pivotallyattached at one end to said support and at the other end to saidintermediate member, a connecting member, a pair of links each pivotallyattached at one end to said intermediate member and at the other end tosaid connecting member, and a planimeter running wheel supported by oneof said links in position to operate upon said surface, the means for beheld in various positions of adjustment relative to said surface andrelative to said intermediate member.

6. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, a pair of arms each pivotallyattached at one end to said support and at the other end to saidintermediate member, a connecting member, a pair of links each pivotallyattached at one end to said intermediate member and at the other end tosaid connecting member, and a planimeter running wheel supported by oneof said links in position to operate upon said surface, the means forsupporting said planimeter wheel upon one of said links comprising aframe formed with bearings for said wheel and formed with a passagethrough which said supporting link passes.

7. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, a pair of arms each pivotallyattached at one end to said support and at the other end to saidintermediate member, a connecting member, a pair of links each pivotallyattached at one end to said intermediate member and at the other end tosaid connecting member, and a planimeter running Wheel supported by oneof said links in position to operate upon said surface, the means forsupporting said planimeter wheel upon one of said links comprising aframe formed with bearings for said wheel and formed with means forpivotally and slidably attaching said frame to said supporting link.

8. In an instrument of the type described adapted for use in connenctionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, a pair of arms each pivotallyattached at one end to said intermediate member, a link pivotallyattached at one end to said intermediate member, and a planimeterrunning wheel supported upon said link in position to operate upon saidsurface, the means for supporting said planimeter running wheel fromsaid link comprising a frame formed with bearings for said wheel andwith meansfor pivotally attaching said frame to the supporting link sothat the running wheel may be moved away from said surface when not inuse.

9. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, a pair of arms each pivotallyattached at one end to said support and at the other end to saidintermediate member, a link pivotally attached at one end to saidintermediate member, a planimeter running wheel supported upon said linkin position to operate upon said surface, and tracing point meansadapted to be guided around the periphery of an area to be measured bysaid planimeter carried by the said link.

10. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto 'said surface, an intermediate member, means for pivotally supportingsaid intermediate member relative to said support said intermediatemember supporting means being so constructed and arranged that saidintermediate member will in all positions remain parallel to itsoriginal position, a planimeter tracing point carrying member, arm meansfor pivotally connecting said tracing point carrying member relative tosaid intermediate member said arm means being so constructed andarranged that said tracing point carrying member will in all positionsremain parallel to its original position, and a planimeter running wheelsupported by said arm means in position to operate upon said surface.

11. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, means for pivotally supportingsaid intermediate member relative to said support said intermediatemember supporting means being so constructed and arranged that saidintermediate member will in all positions remain parallel to itsoriginal position, a planimeter tracing point carrying member, arm meansfor pivotally connecting said tracing point carrying member relative tosaid intermediate member said arm means being so constructed andarranged that said tracing point carrying member will in all positionsremain parallel to its original position, and a planimeter running Wheelsupported by said arm means in position to operate upon said surface,the means for supporting said planimeter running wheel upon said armmeans comprising a frame formed with bearings for said Wheel and withmeans for attaching said frame to the arm means at different distancesfrom the intermediate member.

12. In an instrument of the type described adapted for use in connectionwith a plane surface, a support adapted for attachment in fixed relationto said surface, an intermediate member, means for pivotally supportingsaid intermediate member relative to said support said intermediatemember supporting means being so constructed and arranged that saidintermediate member will in all positions remain parallel to itsoriginal position, arm means pivotally attached to said intermediatemember, a planimeter running wheel supported by said arm means inposition to operate upon said surface, and tracing point means, carriedby said arm means, adapted to be guided around the periphery of an areato be measured by said planimeter running wheel.

